More than a dozen parents who lost their children in the mass shooting at Sandy Hook Elementary School in December spoke candidly about their grief and hopes for the future on "60 Minutes"

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Jimmy Greene and Nelba Marquez-Greene, parents of Sandy Hook School shooting victim Ana, spoke candidly on "60 Minutes" Sunday about losing their daughter. They were among more than a dozen other victims' family members who appeared on the program.

More than a dozen Newtown parents directly and tragically linked to the mass shooting at Sandy Hook Elementary, candidly recalled the December day that changed their lives in an emotional "60 Minutes" segment that aired Sunday night.

They spoke of frantic phone calls and fraying nerves as the day wore on and parents gathered at the local firehouse had still not located their children.

"There were people everywhere ... and you really had to push to get through," said Nicole Hockley, the mother of one of the first-graders in Victoria Soto's class, killed in the attack. "We were all just jostling because we were trying to find our kids."

The interview aired on the eve of a big lobbying day for gun control supporters, which brought President Barack Obama to the University of Hartford and will send 11 relatives of Sandy Hook victims, including Hockley, to Washington where they will push for federal gun control legislation. In the "60 Minutes" segment, parents and relatives made an emotional plea for more stringent background checks and limits to the size of ammunition magazines.

"You can have a million bullets but if you have to put them in one at a time, the ability to do any kind of real damage is significantly reduced," said Bill Sherlock, the husband of Sandy Hook school psychologist Mary Sherlock, who died confronting shooter Adam Lanza. "It's simple arithmetic. If you have to change magazines 15 times instead of five times you have three more instances where something could jam," something could go wrong and potential victims can escape as 11 students did during a lull in Lanza's shooting rampage, he added.

While the gun control debate was certainly the backdrop of the interview and what called the victims' relatives to the studio, the focus, more than anything, remained fixed on the memory of their children and loved ones, and their experiences on and since Dec. 14.

Hockley remembered the relief of finding her son Jake, suddenly shattered by the uncomfortable reminder that her other son Dylan, who had not yet been found, may not have survived.

"A woman asked me, 'what classroom was your other child in?' And I said, Miss Soto's. And she said, 'I heard she got shot.' And I got really angry at her and I remember very clearly saying, 'don't you dare say that to me if you don't know it's true.'" Hockley said. Teacher Victoria Soto did in fact die in the attack.

"I just pushed by her but I couldn't find Dylan's classroom or anyone from his class anywhere," said Hockley.

It was Gov. Dannel Malloy who finally, hours after the last shots were fired, broke the news to parents gathered in a back room at the firehouse.

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"[He] had the duty to stand in front of the room and tell us that if we were in that room then our child or adult wasn't coming back to us," Hockley recalled.

Jimmy Greene, the father of Ana Marquez-Greene, who also died in the shooting, spoke about finding his other child, who also attended Sandy Hook, safe and terrified.

"I saw my son's teacher in a living room area ... Isaiah popped up and I just went and grabbed him and held him and he was crying, 'Daddy, you know, there were so many gunshots. I saw this and I saw that,'" Greene recalled. "So I just took my son in my arms—he's a big kid, but I took him like he was two years old again and held him on my shoulder and was just running and running from room to room trying to locate Ana's class."

"I knew what the back room meant. In my heart, as a mother, I knew what the back room meant."

Some of the most touching testimony regarded how the parents are coping with the absence of the quirky kids who were at the center of their lives.

Francine Wheeler said she dreams of her son Benjamin all the time. "And we talk," she said. "And he and I talk when I take my walks. And I just feel him. If I ask him to be present he is. And I know he'll always be there."

Jackie Barden said she feels distance growing between her and her son Daniel, who died in the shooting. "Sometimes it's too painful to think about him. And then I feel guilty because I need to think about him and keep him alive, but it's so hard because we miss him so much."

Nicole Hockley said that she keeps Dylan's cremated remains next to his photo in her bedroom. "Every morning I kiss him good morning and say hi. And he's the last thing I kiss before I go to bed at night. And every night I beg for him to come to me in my dreams so I can see him again. And during the day, I just focus on what I can do to honor him and make change."

Hockley and 10 other members of the Sandy Hook Promise, a non-profit pushing for federal gun control legislation, will fly aboard Air Force 1 with the president to Washington Monday night, where they will spend the week lobbying Congress for change. They represent nine victims killed in the Sandy Hook shooting.